Process for the treatment of vanadium-bearing ores



Patented Sept. 20, 1949 PROCESS FOR THE TREATMENT OF VANA- DIUM-BEARING ORES Ragnvald Asak, Vestre Aker, near Oslo, Norway, assignor to Christiania Spigerverk, Nydalen,

near Oslo, Norway No Drawing. Application March 29,

In Norway July 1939 Section 1, Public Law Patent expires 1 Claim.

The present invention relates to a process for the treatment of vanadium-bearing iron ores and in particular to an improved method of freeing the vanadium from its spinel-like association with the iron by heating the ore in a porous state with reducing carbon to reduce only the iron and subsequently to oxidize both iron and vanadium to leachable vanadate.

It is formerly known to roast vanadium-bearing ores, for example titanium-bearing iron ores in the presence of alkali compounds, for example soda, sodium chloride or nitrate or mixtures thereof, whereby alkali vanadate is obtained, which is lixiviated.

However, none of these processes are workable in practise when the vanadium content is low, for example 1%. Besides, sticking during the roasting cannot be avoided, which causes breakdowns and excessive wear and tear of the machinery and the furnaces and consequently increased repair costs. Further, the roasting air will not penetrate to the grains through the sticking layer, with resulting incomplete oxidation.

The drawbacks referred to above are obviated by the present invention.

According to the invention the ground ore together with an alkali compound is mixed with a carbonaceous material, for example charcoal, coke or coke breeze.

Thus heat is supplied to the material in a very convenient manner for the desired reactions, and simultaneously the mixture becomes more porous, thereby facilitating the admission of air and the oxidation of the lower oxides in the oxidation step. The carbonaceous material may be added 1946, Serial 690, August 8, 1946 July 1, 1959 before or during the roasting operation. At the preliminary reduction which occurs on introducing air, part of the carbon has a reducing effect on the iron oxide, while the vanadium oxide is not reduced, but is liberated from its spinel-like compound with the iron and possible other metals which may be present.

In the subsequent oxidation step the admission of air is controlled in such a way, that the vanadium is oxidised to a higher oxide, which combines with the alkali to alkali vanadate, while simultaneously the lower iron oxides or iron metal obtained by the reduction are oxidised to F6203. The alkali vanadate is washed out and the solution further treated in a manner known per se.

In case the process is used in connection with an ore of such a kind that also the iron and in case the titanium content of the ore should be utilised, the roasted and lixiviated material, which is free of sulphur, may be subjected to a reducing treatment, whereby the iron oxide is reduced to metal, eventually in blast furnaces or electric pig iron furnaces. After lixiviation, the iron sponge may then be separated magnetically. From the solution and residue vanadic acid and titanium compounds, for instance, titanic acid, are then reduced in a manner known per se.

Some roasting tests with vanadium bearing iron ore with or without additions of charcoal or coke 30 breeze are reported below.

Table I Roasting tests with vanadium bearing iron ore without addition of charcoal, coke breeze or the like.

[The tests were efiected in an electrically heated furnaca] Percent Percent Percent Temp., Roasting Percent Gram size NaOl NBiSOI KNO: Degree 0. time, hours Yield 25% between 100 and 200 mesh. 10 800 4% 52 75% finer than 200 mesh 14 800 4% 43. 4 130---- 17 800 4 41.7 Do... 20 800 4% 48. 7 Do. 20 800 4% 41. 2 D 0.-- 20 800 4 2 36. 2 Do..- 15 800 4% 32. 4 Do 13 860 4% 33. 8 D 10 800 4% 38. 2 Do 800 4% 58. 8 Do--. 4 800 4% 67. D0.-. 4 850 4% 65.0 Do-.. 4 900 4% 65. 8 Do..- 4 950 4% 64. 2 Do" 850 4% 65. 9 130.- 850 4 z 65. 9 D0".-- 850 4 2 64. 5 Do 10 850 4% 65. O 130.- 15 850 4% 66. 0 D0. 20 850 4% 65.2 Fine! th 10 850 4% 68. 5 D 20 850 4% 68. 0 D 800 4% 65. 2 D 850 4% 68. 8 Dn 850 4% 60. 0 Dn 850 4% 58. 4

i :Zlable I! Roasting test "with vanadium bearing iron are with added coke breeze or charcoal.

' Percent mutating Per cent Per cent 3cl1ara Gram slze coke time, 3 yiellfidf Soda breeze hours vanadium "2 "95.3 2% 92.3 2y 32.5 2% $74.8 2% 100:0 2% 94.0 a 2 7 9030 2 19253 2 9550 2 93.0 2 x 91.0

In the tests in Table I -the roasting product agglomerated orcodlescedsitrongly and the Alanadium ,yield .not exceed 20%, even ore ground \down'to atgrain sizefiner than 200 mesh.

As being evident from Example TII an addition ofcoke breeze or charcoal to themasting material results .-in an increased Man-amum .yieid o fifrom about 70 .%-a.bout 951%111 using as'horter roasting time even with less finely ground ore, sticking .heing simultaneously prevented, whereby iii; becomes possible to undertake the roasting in retating iurnaces, stepgrate furnaces, etc.

It will tbenotedifrom .the second example above performed .upon .a .iynical vanadium containing iron one the ptimum quantity at each of vsoda and charcoal may "be in the range of 'I0%-I5% 3 with respect to the ore.

@rozcess of producing sdlulile vanadium compounds from vanadium bearing iron ores com- ,prising mixing the granulated ore with an alkali metal compound in quantity sufficient to react "with the vanadium oxide content of the ore and a porous carbon material selected from the group icunsisting of ichawcoal and coke and heating the mixture firs't with -=a limited supply of air to eifect 10 a preliminary reduction of the metal content of :the tore vether zthan vanadium to free the unmeduced vanadium oxide from its spinel-like compound with the iron, then heating the mixture with :2, tree supply of air to oxidize both the --1 vanadium to its higher oxide to form vanadates by reaction with the alkali compound and the iron to iron oxide (Re-203), and leaching thesoluhle vanadate from the ore. I r

' 'RAGNVALD A-SAK REFERENCES GITED ilfhe following references are of record in the .filenf this patent: r

Great Britain tray 15,1934 

